If the bond energies of H-H, Br-Br, and H-Br are 433, 192 and 364 kJ mol^-1 respectively, 

the $∆\mathrm{H}°$ for the reaction

H₂(g) + Br₂(g) $\to$2HBr(g) is

For a given reaction, $∆$H =35.5 kJ mol^-1 and $∆$S = 83.6JK^-1 mol^-1. The reaction is spontaneous at:
(Assume that $∆$H and $∆$S do not vary with temperature)

A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy $∆$U of the gas in joules will be

For a sample of perfect gas when its pressure is changed isothermally from p_i to p_f, the entropy change is given by

The correct thermodynamic conditions for the spontaneous reaction at all temperatures is

$$\begin{gathered} \left(\mathrm{a}\right) ∆\mathrm{H}>0 \mathrm{and} ∆\mathrm{S}<0 \\ \left(\mathrm{b}\right) ∆\mathrm{H}<0 \mathrm{and} ∆\mathrm{S}>0 \\ \left(\mathrm{c}\right) ∆\mathrm{H}<0 \mathrm{and} ∆\mathrm{S}<0 \\ \left(\mathrm{d}\right) ∆\mathrm{H}<0 \mathrm{and} ∆\mathrm{S}=0 \end{gathered}$$

The heat of combustion of carbon to CO₂ is -393.5 kJ/mol. The heat released upon the

formation of 35.2 g of CO₂ from carbon and oxygen gas is

For the reaction, X₂O₄(l) $\to$2XO₂(g)

$∆$U = 2.1 kcal, $∆$S = 20 cal K^-1 at 300 K. Hence, $∆$G is

If the enthalpy change for the transition of liquid water to steam is 30 kJ mol^-1 at 27°C,

the entropy change for the process would be

For which process will $∆$H° and $∆$G° be expected to be most similar.

In thermodynamics, a process is called reversible when

Which of the following is correct option for free expansion of an ideal gas under adiabatic condition?

$$\begin{gathered} \left(1\right) \mathrm{q}\ne 0, ∆\mathrm{T} =0, \mathrm{W}=0 \\ \left(2\right) \mathrm{q}=0, ∆\mathrm{T} =0, \mathrm{W}=0 \\ \left(3\right) \mathrm{q}=0, ∆\mathrm{T} <0, \mathrm{W}\ne 0 \\ \left(4\right) \mathrm{q}=0, ∆\mathrm{T}\ne 0, \mathrm{W}=0 \end{gathered}$$

Enthalpy change for the reaction,

 4H(g) $\to$2H₂(g) is -869.6 kJ

The dissociation energy of H-H bond is

From the following bond energies:

H-H bond energy: 431.37 kJ mol^-1

C=C bond energy : 606.10 kJ mol^-1

C-C bond energy : 336.49 kJ mol^-1

C-H bond energy : 410.50 kJ mol^-1

Enthalpy for the reaction,

$\underset{\underset{\mathrm{H}}{|}}{\overset{\stackrel{\mathrm{H}}{|}}{\mathrm{C}}}=\underset{\underset{\mathrm{H}}{|}}{\overset{\stackrel{\mathrm{H}}{|}}{\mathrm{C}}}+\mathrm{H}-\mathrm{H}\to \mathrm{H}-\stackrel{\stackrel{\mathrm{H}}{|}}{\underset{\underset{\mathrm{H}}{|}}{\mathrm{C}}}-\underset{\underset{\mathrm{H}}{|}}{\overset{\stackrel{\mathrm{H}}{|}}{\mathrm{C}}}-\mathrm{H}$

will be

The values of $∆$H and $∆$S for the reaction, 

C(graphite) + CO₂(g) $\to$2CO(g) are 170 kJ and 170 JK^-1, respectively. This reaction will

be spontaneous at

Which of the following are not state functions?

(I) q + W                        (II) q

(III) W                           (IV) H-TS

Consider the following reactions :

(i) ${\mathrm{H}}^{+}\left(\mathrm{aq}\right) + {\mathrm{OH}}^{-}\left(\mathrm{aq}\right) = {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) ∆\mathrm{H} = -{\mathrm{x}}_1 \mathrm{kJ} {\mathrm{mol}}^{-1}$

(ii) ${\mathrm{H}}_2\left(\mathrm{g}\right) + \frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right) = {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) ∆\mathrm{H} = -{\mathrm{x}}_2 \mathrm{kJ} {\mathrm{mol}}^{-1}$

(iii) ${\mathrm{CO}}_2\left(\mathrm{g}\right) + {\mathrm{H}}_2\left(\mathrm{g}\right) = \mathrm{CO}\left(\mathrm{g}\right) + {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) ∆\mathrm{H} = -{\mathrm{x}}_{3 }\mathrm{kJ} {\mathrm{mol}}^{-1}$

(iv) ${\mathrm{C}}_2{\mathrm{H}}_5\left(\mathrm{g}\right) + \frac{5}{2}{\mathrm{O}}_2\left(\mathrm{g}\right) = 2{\mathrm{CO}}_2\left(\mathrm{g}\right) + {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) ∆\mathrm{H} = -{\mathrm{x}}_4 \mathrm{kJ} {\mathrm{mol}}^{-1}$

Enthalpy of formation of H₂O(l) is:

Identify the correct statement for change of Gibbs energy for a system ($∆$G_system) at constant temperature and pressure:

The enthalpy and entropy change for the reaction :

Br₂ (l) + Cl₂ (g)$\to$ 2BrCl (g)

are 30 kJ mol^-1 and 105 J K^-1 mol^-1 respectively.

The temperature at which the reaction will be in equilibrium is :

The enthalpy of combustion of H₂, cyclohexene (C₆H₁₀) and cyclohexane (C₆H₁₂) are -241, -3800 and -3920 kJ per mol respectively. Heat of hydrogenation of cyclohexene is:

Consider the reactionat 300K

H₂₍₉₎ + Cl₂₍₉₎ →2HCI_(g), ΔH° = — 185 KJ

If 3 mole of H₂ completely react with 3 mol of Cl₂ to form Cl, $∆$U° of the reaction will be

For a perfectly crystalline solid C_pm = aT³, where a is constant. If C_pm is 0.42 J/K–mol at 10 K, molar entropy at 10 K is

One mole of an ideal monoatomic gas expands isothermally against constant external pressure of 1 atm from initial volume of 1L to a state where its final pressure becomes equal to external pressure. If initial temperature of gas is 300 K then total entropy change of system in the above process is :

[R = 0.082 L atm mol^–1 K^–1 = 8.3 J mo1^–1K^–1].

At 1000 K water vapour at 1 atm. has been found to be dissociated into H₂ and O₂ to the extent of 3 x 10^–6 %.Calculate the free energy decrease of the system, assuming ideal behaviour.

An ideal gas is taken from the same initial pressure P₁ to the same final pressure P₂ by three different processes. If it is known that point 1 corresponds to a reversible adiabatic and point 2 corresponds to a single stage adiabatic then

During winters, moisture condenses in the form of dew and can be seen on plant leaves and grass. The entropy of the system in such cases decreases as liquids possess lesser disorder as compared to gases. With reference to the second law, which statement is correct, for the above process ?

The occurrence of a reaction is impossible if -

A copper block of mass `m' at temperature 'T<sub>1</sub>' is kept in the open atmosphere at temperature `T₂' where T₂ > T₁ . The variation of entropy of the copperblock with time is best illustrated by

The heat produced in calories by the combustion of one gram of carbon is called

For the isothermal expansion of an ideal gas

If a refrigerator's door is opened, then we get